Synchronous motor



May 25, 1937. H. M. STQLLER m. 2,081, 1-

Original Filed July 21, 1933 2 Sheets-Sheet l H. M. STOLLER WVENTORS' ER. MORTON Brigham A TTORNEV May 25 1937- H. M. 'STOLLER ET AL.

smcnaonous MOTOR 2 Shee ts-Sheet 2 Original Filed July 21, 1953 ATTORNEY Patented May 25, 1937 UNITED STATES PATENT OFFICE 2,081,411 sYNonnoNoUs' MOTOR Hugh M. Stoller, Mountain Lakes, N. J., and Edmund R. Morton, New York, N. Y.. assignors to Bell Telephone Laboratories, Incorporated, New York, N. Y., a corporation of New York Original application July 21, 1933, Serial No.

Divided and this application September 21, 1935, Serial No. 41,518

2 Claims.

invention are improvements over the timing de- 1 vice disclosed in G. T. Kirby application Serial No. 620,437.

The object of this invention, therefore, is to provide improved means for accurately determining the time taken for a race or other event.

The improvements constituting this invention reside in a synchronous motor, the motor being employed to drive a chronometer.

A feature of this invention resides in the magnetic structure of the motor.

The invention may be used in conjunction with a chronometer combined with a motion picture camera when it is desired to have pictures of an event and a record of the elapsed time appear on the same motion picture film, or it may be used with a chronometer exclusive of the camera when only time records are required.

A clutch forming the subject-matter of our Patent 2,019,638, issued November 5, 1935 and of which this application is a division is provided to couple the synchronous motor to the chronometer.

In the drawings: Fig. 1 is a view in perspective of the synchronous motor combined in a unitary structure with the clutch;

Fig. 2 is a side elevational view of the synchronous motor, partly in section; V

Fig. 3 is an elevational view of the back of the synchronous motor; and

Fig. 4 is a view in perspective of the clutch including a polarized clutch operating magnet.

In timing races and other events with this apparatus the synchronous motor is started some time before the beginning of the event. A starting signal is then given to start the event. When.

Pictures are then taken of the event and the chronometer dials. In each frame of the motion picture film, therefore, there appears an image of the contestant, or contestants as the line is approached or crossed and a picture of the chronometer dials showing them in their relative positions with respect to some predetermined point at the time the picture was taken.

To more clearly point out the improvements in which this invention resides, reference will now be had to the drawings.

The chronometer is driven by means of the synchronous motor 6 which is combined with the clutch 'I and the polarized clutch operating magnet 66 in the unitary structure'as shown in Figs. 1 and 4. The synchronous motor 6 is a non-self-starting synchronous motor and comprises a set of U-shaped laminated pole-pieces 69, a set of permanent magnets I15, shown in Figs. 2 and 3, a cylindrical rotor I0 and a pair of operating .coils II to alternately aifect the magnetism of the pole-pieces 69. The free ends of the pole-pieces 69 are machined out at their adjacent inward faces to provide a. cylindrical aperture 65 to accommodate the rotor 10. The polepieces'GS are provided with arcuately arranged protuberances I2 which project into the magnetic field. Operating within the cylindrical aperture 65 formed between the free ends of pole-pieces 69 is the cylindrical rotor III which has peripheral projections I3 extending radially toward the protuberances I2 of the pole-pieces 69. The number and spacing of the proturberances I2 of the pole-pieces 6 9 and the number and spacing of the peripheral projections I3 on the rotor III are so arranged that when the peripheral projections I3 on one side of the rotor III are in alignment with the inwardly projecting protuberances I2 of one pole-piece, the peripheral projections'13 on the other side of the rotor III are not in alignment with the inwardly projecting protuberances I2 of the other pole-piece. Connected to the closed end of the laminated pole-pieces 69 by means of a plate I14 is a set of bar magnets I15 which are permanently magnetized. The bar magnets I15 are arranged in parallel and extend parallel to the leg portions of the laminated pole-pieces G9. The south pole ends of the bar magnets I15 terminate in the plate I I4 and the.

. pieces 69. Attached to the north pole ends of the bar magnets I15 is a plug member I16 of magnetic material. The cylindrical rotor III comprises a cup member 68 on the periphery of which is secured a ring I18 of magnetic material. On the periphery of the ring I18 are the projections 18 which extend radially of the rotor 18 toward the pole-pieces 68. The plug I16 is provided with a centrally located sleeve bearing I18 adapted to receive a shaft 16 which is secured at I88 to the bottom of the cup member 68. 1 The shaft 16 extends inward within the center of the cup member 68'to form a pin portion I 8| which is journalled in the sleeve bearing I18 of the plug I16. The shaft 16 projects beyond the bottom of the cup member 88.

The plug I16 forms a central north pole end of the stator assembly of the motor. The leg portions of the U-shaped pole-pieces 68 form south poles on opposite sides of the rotor. The

magnetic circuit is therefore divided and may be traced from the north pole ends of the bar magnets I16 through the plug I16, across the small air-gap between the periphery of the plug I16 and the inner wall of the cup 18, through the cup 18 to the laminated ring of magnetic material |18 on the outside of the cup, through the peripheral projections 13 of the ring I18, across an air-gap between the ring I18 and the leg portions of the U-shaped pole-pieces 68, through the pole-pieces 68 by way of the protuberances 12 and thence through the plate I14 to the south pole ends of the bar magnets I15. Each leg of the U-shaped pole-piece member by reason of its connection with the south pole ends of the bar magnets forms in normal condition a permanently magnetized south pole. An operating coil 1| is provided on each leg portion of the U-shaped member. The coils 1| are connected to a suitable source of alternating current. When the coils 1| are energized the magnetic flux in one I of the legs of the U-shaped member is partially neutralized whereas in the opposite leg of the U-shaped member the flux is reenforced. This reduces the magnetic attraction between the projecting protuberances 12 of the leg portion of the U-shaped member and the peripheral projections 18 on one side of the rotor 18 and increases the magnetic attraction between the projecting protuberances 12 and the peripheral projections 13 on the other side of the rotor 18 thereby releasing the aligning magnetic force between the protuberances 12 and projections 13 on the one side of the rotor and increasing the magnetic pull between the protuberances 12 and projections 13 on the other side of the rotor 18 to bring the protuberances 12 and projections 13 on the last-mentioned side into alignment. nally imparted to the rotor 18, therefore, is continued by the alternate changes in the magnetic structure caused by the alternating currentap plied to the operating coils 1|. While a plurality of protuberances 12 are shown on each leg portion of the U-shap'ed member a single protuberance 12 on each leg portion might be found adequate for the purpose.

The motor 6 is secured to a rectangular frame 14 as shown in Fig. 1 by means of screws 15. The shaft 16 is journalled in a boss 11 of the frame 14 as shown in Fig. 2 and extends outward beyond the flat surface of the frame. Secured to the outer extremity of the shaft 16 is a pinion 18 the teeth of which engage a comparatively large gear 18, shown in Fig. 1 which, as will be subsequently described, serves to drive a clutch member.-

Secured to the outer flat face of the rectangular frame 14 by means of the screws 88 is an L-shaped bracket 8| which terminates at its free end in with the ratchet wheel 86.

The rotation origispaced bosses 82 and 83. Secured within the boss 82 and extending inwardly therefrom toward the flat face of the frame 14 is a pin 84 on which is revolvably supported a comparatively large gear 18 which is permanently engaged by the pinion 18. Secured to the outer face of the large gear 18 by means of the pins is a ratchet wheel 86. The ratchet wheel 86 serves in conjunction with other means to be subsequently described to provide a means for manually rotating the cylindrical rotor 18 of the motor 6.

The frame 14 terminates in one end in a plate portion 81 shown in Fig. 1 as being integral with the frame 14. The plate portion 81 is provided with an elongated arcuately shaped aperture 88 and an elongated straight aperture 88. Journalled in a boss 88 in the plate portion 81 and projecting normal to the plane of the plate portion 81 is a shaft 8|. Attached to the outer end of the shaft 8| is a handle 82 which may be manually operated to rotate the shaft 8| when the synchronous motor 6 is to be started. Attached to the center of the shaft 8| and projecting normal to the axis of the shaft 8| is an L-shaped arm 83 the free end of which projects through the elongated arcuately shaped aperture 88 in the plate portion 81. The arm 83 is manually operated by means of the handle 82 against the action of a spring 84, the spring 84 being attached at one end to the arm 88 and having the other end attached to a screw .85 which is adjustable within the elongated straight aperture 88 in the plate portion 81 of the frame 14. Attached to the arm 83 and extending normal therefrom is a pawl 86 the free end of which may be brought into engagement with the ratchet wheel 86. To start the synchronous motor 6, the handle 82 is manually moved toward the right until the free end of the arm 83 reaches the end of the elongated arcuately shaped aperture 88. By this movement the pawl 86 is brought into engagement with the ratchet wheel 86. When the handle 82' is released the spring 84 returns the arm 83 to normal position and in so doing presses the pawl 86 against the teeth of the ratchet wheel 86. The ratchet wheel 86 is therefore driven by the spring-operated pawl 86 until the pawl 86 passes in its arc of movement out of engagement Since the ratchet wheel 86 is pinned to the large gear 18, rotation of the ratchet wheel 86 causes rotation of the large gear 18 and rotation of the pinion 18 which is attached to the shaft 16 extending axially from the cylindrical rotor 18 of the synchronous motor 6. When the synchronous motor 6 has thus been manually started, the rotor 18 is continued in its rotation by the continuously changing current in the operating coils 1|.

Adjustably secured within the boss 83 of the L-shaped bracket 8| is a screw 81 which serves as an adjustable bearing for shaft I82. The shaft I82 extends through an aperture in the frame 14 and runs parallel with an arm I88 which is integral with the frame 14. The arm I88 extends backward of the frame 14 and terminates at its free end in an upturned end portion I I8. The upturned end portion I I8 supports a bearing II I, an adjustment screw I83 and a set screw I84. The shaft I82 is supported at one end by the screw Bland at the other end by the bearing III and may be adjusted longitudinally by means of the screws'81 and I88.

Between the free end of the L-shaped bracket 8| and the frame 14 and supported by the shaft I82 is an annular clutch member 88. The annular ,with the teeth of the large gear 19. The clutch member 98 has a hub portion I00 which is pinned to the shaft I82. The clutch member 96 is provided with clutch teeth on its inner face IOI,' the teeth being directed axially toward the rectangular frame I4 and having their edges radial with respect to the shaft I82. An annular stop clutch member I02 with teeth corresponding in number and spacing to the teeth on the inner face IOI of the clutch member 98 is secured to the rectangular frame 14 by means of the screws I03. The teeth on the annular stop clutch member I02 extend axially toward the clutch member 98 and have their edges radial to the shaft I62 and are inclined conjugately to the teeth on the inner face IOI of the annular clutch member 98. The annular clutch member 98 and the stop clutch member I02 are spaced apart a sufiicient distance to permit a flyer arm clutch member I05 to be operated between them. The flyer arm clutch member I05 is attached to an annular hub I85 which forms one end of a tubular shaft 3.. The tubular shaft II3 extends parallel to the arm I09 and encloses the shaft I82 and is provided with internal bearing surfaces in each end. The shaft I82 is normally rotated within the tubular shaft H3 and the tubular shaft II3 may be moved longitudinally along the shaft I82. The'flyer arm clutch member I05 is moved from one to the other of the clutch members 98 and I02 by means of the polarized clutch operating magnet66. The polarized clutch operating magnet 66 is attached to the rectangular frame I4 by means of a bracket- I06 and has spaced pole-pieces I01, a permanent bar magnet I66 and operating coils I08 extending parallel to the rectangular frame I4. The tubular shaft II3 extends through bifurcated ends in the pole-pieces I01 and through the center of the annular stop clutch member I02. Be-

tween the pole-pieces I01 and attached to the shaft I I3 is a cylindrical armature III which is attracted toward one or the other of the polepieces I01 when the polarized clutch operating magnet 66 is operated. The tubular shaft II3,

therefore, is longitudinally moved by operation of the polarized clutch operating magnet 66.

What is claimed is:

1. In an apparatus of the class described a synchronous motor comprising a set of permanent magnets, pole-pieces connected to said magnets, energizing coils on said pole-pieces to vary the magnetic flux, a rotor operating between said pole-pieces and a plug member attached to ends of said permanent magnets and projecting within said rotor said plug member forming part of a magnetic circuit for the motor.

2. In an apparatus of the class described a synchronous motor comprising a set of bar magnets permanently magnetized, U-shaped polepieces connected to end portions of said bar magnets, energizing coils on said pole-pieces to vary the magnetic flux, a rotor operating between said pole-pieces, said rotor being hollowed out in the centre and a plug member attached to said bar I magnets and projecting into the hollowed out portion of said rotor said plug member forming part of the magnetic circuit of said motor.

HUGH M. STOLLER. EDMUND R. MORTON. 

